Amazing Audio Illusion

Play this audio clip again after it finishes and hear it continue to “creep up”.

See Wikipedia’s entry on Shepard Tone for the full scoop.

A Shepard tone, named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When played with the base pitch of the tone moving upwards or downwards, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that continually ascends or descends in pitch, yet which ultimately seems to get no higher or lower.

The Stroop Effect

The Stroop Effect, named after J. Ridley Stroop who published the effect in 1935, is a demonstration of interference in the reaction time of a task. For example, when a word signifying a colour such as “red” is printed in blue a reader’s reaction time processing the word’s colour, leads to slower test reaction times and an increase in mistakes.

Try out one of my favourite demonstrations of this effect by saying the colours of the words below:

(For example if the word “blue” is printed in green, you would say the word green)

   red     blue    orange    yellow    purple    green    blue    yellow    red    blue    orange    purple    yellow    green    blue    red    green    orange    purple
   yellow    orange    red    green    blue    green    red    green    blue    yellow    orange    purple    green    blue    yellow    red    orange    purple    green

If naming the first group of colours is easier and quicker than the second, then your performance exhibits the Stroop effect.

The Stroop effect illustrates important principles about how the brain works, particularly for mental tasks involving attention, automatic processing, and response selection. It also can be used to examine the subtle effects of adverse conditions on the brain, such as lack of sleep, fatigue, or the effects of high altitudes.

The coloured word test above is only one kind kind of automatic processing that can be studied.

Check out Harvard University’s site in which they continually collects data with their Implicit Association Tests, many of which have fascinating social and political implications.

The Truth About Subliminal Influence

Hungry? Eat Popcorn

The interesting thing about the claim of a subliminal influence contained within popular music when played backwards is that the messages are very difficult (if not impossible) to discern unless you’ve been primed to hear them on a conscious level.

I’ve been receiving emails wanting to know how this apparent lack of influence ties in with research that demonstrates subliminal messages can coerce unwary buyers into making purchases they would not otherwise have considered?

A short story is in order, (stop me if you’ve heard this one) Fort Lee, N.J., 1957. Unsuspecting film goers are enjoying “Picnic”, with William Holden and Kim Novak. In the projection room, an important marketing experiment is being staged. Researcher James Vicary has installed a tachistoscope, a machine that can inject subliminal images of tiny fractions of a second—far below that of a person’s conscious threshold. Every five seconds and for a duration of just 1/3000th of a second, Vicary alternated two messages. One read, “Drink Coca-cola” and the other, “Hungry? Eat Popcorn”.

Vicary’s results were spectacular! Coca-cola sales jumped 18.1%; popcorn sales 57.8%. Vicary dubbed this “subliminal advertising”, the practise of manipulating consumers to make purchases they might not normally make.

And if you believe that, I’ve got a pet rock I’d like to sell you.

The great popcorn experiment was a fraud.

Advertisers and regulators doubted Vicary’s story from the beginning, so another researcher, Dr. Henry Link, duplicated Vicary’s experiment and found no evidence that people reacted to the messages. In a 1962 interview, Mr. Vicary admitted the data was all fabricated to gain attention for his business. Some critics have since expressed doubt that he ever conducted the experiments at all.

However, the legend lives on. To this day a great many people still believe Vicary’s claims and will apparently never be convinced otherwise.

As numerous studies over the last few decades have demonstrated, subliminal advertising doesn’t work; in fact, it never worked, and the whole premise was based on a lie from the very beginning.

It is possible to prime the unconscious.

According to a recent experiment, psychologists at Yale were able to alter people’s judgments by simply priming them with either hot or cold coffee.

The study participants, college students, had no idea that their social instincts were being deliberately manipulated. On the way to the laboratory, they had bumped into a laboratory assistant, who was holding textbooks, a clipboard, papers and a cup of hot or iced coffee and asked for a hand with the cup.

That was all it took: The students who held a cup of iced coffee rated a hypothetical person they later read about as being much colder, less social and more selfish than did their fellow students, who had momentarily held a cup of hot java.

As improbable as it may seem, findings like this one have continued to pour forth in psychological research in recent years.

New studies have found that people tidy up more thoroughly when there’s a faint tang of cleaning liquid in the air; they become more competitive if there’s a briefcase in sight, or more cooperative if they glimpse words like “dependable” and “support” all without being aware of the change, or what prompted it.

The article goes on to remind readers that, “studies of products promising subliminal improvement, for things like memory and self-esteem, found no effect”.

If you’re interested in this sort of thing, I recommend reading Malcolm Gladwell’s book, Blink—here’s a very short audio snippet from chapter 2 (650k mp3).

Subliminal Messages Psychology Materials

I occasionally get requests for materials for psychology classrooms based on the backmasking section of my website. I usually don’t send out materials, but I have been known to make exceptions, especially for professors of post secondary institutions.

I should point out that if you are teaching psychology, you may be interested in material intended for classroom demonstrations by writing John Vokey or Don Read at

Department of Psychology, University of Lethbridge, Lethbridge, Alberta T1K 3M4 Canada

and requesting University of Lethbridge, Department of Psychology, Technical Report No. 85. A blank cassette tape should be enclosed if classroom demonstrations are desired.

I imagine a blank CD would also work or maybe an empty USB thumb drive, but I would ask them first just to be safe.

Jay-Z and his Unconscious Influence

I came across a video clip of a preacher speaking out against the Hip Hop artist Jay-Z. Proponents of the evils of backmasking, like this preacher, argue that the effects of listening to music with backward messages are manifested in an unconscious manner on the listener’s subsequent behaviour.

He states that:

the heavy metal folks used to do that and they would put the backwards masked messages in your music and they’d say that your subconscious is smart enough—that right brain was smart enough to decode and flip that message so by the time it got to your left brain you understood it and you didn’t even know you understood it. You just acted it out. Because they have the song called Another One Bites the Dust—Queen. Played it backwards it said, I like to smoke marijuana. Yeah, and then they interviewed kids and kids say when they listen to it they just wanna get high, they just want to smoke weed and they had no idea that that message was being reversed in their mind and causing them to want to do that.”

I’d like to point out that contrary to this preacher’s claims, studies have shown that it is, in fact, impossible for the subconscious mind to “decode and flip that message”.

In volume 40, No. 11 of American Psychologist (November 1985), psychologist professors John R. Vokey and J. Don Read address the possibility of unconscious influence within reversed audio.

The proponents of backmasking argue that the effects of greatest concern are not the consciously perceived meanings of backward messages but rather those effects arising from unconscious or subliminal apprehension of the (forward) meaning of the material. Consequently, we also used tasks that required less in the way of conscious apprehension of meaning. We reasoned that if some subconscious mechanism existed for the interpretation of backward messages and their influence upon behaviour, then this mechanism should allow decisions to be made about content without necessarily revealing that content.

Their series of properly controlled scientific experiments included:

  • Identifying whether a backward message when played forward was a statement or a question – 52.1% accuracy (50% expected on the basis of random assignment)
  • whether they believed two sentences had the same meaning with only changes in the active or passive voice or whether the two sentences had different meanings — 44.81% accuracy (50% expected on the basis of random assignment)
  • identifying a series of sentences into whether or not they would make sense if heard in the forward direction – 45.2% accuracy (50% expected on the basis of random assignment)
  • categorizing statements of the sort, “Jesus loves me, this I know” into one of five content categories: nursery rhymes, Christian, satanic, pornographic, and advertising. 19.4% accuracy (20% expected on the basis of random assignment)

Upon the completion of their experiments Vokey and Read concluded, “we could find no evidence that our listeners were influenced, consciously or unconsciously, by the content of backward messages.”

I’m not one to deny that it does SOUND like Jay-Z has an anti-religious message in the reverse clip. It’s my belief that if such a message is intentional, its purpose is to gain publicity for his album. By pointing it out, this video has actually done a favour for Jay-Z. The prudent thing to do would be to ignore such obvious attention grabbing tactics. Nevertheless preachers like this one continue to disseminate the false claim that backwards messages within music can influence those listening. I think it’s because that message draws big crowds and allows the preachers to more easily sell copies of their sermons on DVDs.


[Jay-Z Subliminal Message – YouTube]

(Thanks Cody)